Decision Table-based Testing

A precise yet compact way to model complicated logic. Associate conditions with actions to perform. Can associate many independent conditions with several actions in an elegant way

Terminology

• Condition entires restricted to binary values as we have limited entry table.
• Condition entries have more that two values, we have extended entry.

Using Decision Tables in Software Testing

• Condition entries in a decision table are interpreted by a computer program as input, equivalence classes of inputs.
• Action entries in a decision table are interpreted as output, major functional processing portions.
• The rules are then interpreted as test cases.

Decision Table Applicability

• The specification is given or can be converted to a decision table .
• The order in which the predicates are evaluated does not affect the interpretation of the rules or resulting action.
• The order of the rule evaluation has no effect on resulting action .
• Once a rule is satisfied and the action selected, no other rule need be examined.
• The order of executing actions in a satisfied rule is of no consequence.
• In reality, the restrictions do not eliminate many potential applications.
  • In most applications, the order in which the predicates are evaluated is immaterial.
  • Some specific ordering may be more efficient than some other but in general the ordering is not inherent in the program's logic.

Decision Tables - Issues

• Before deriving test cases, ensure that
  • The rules are complete
    • Every combination of predicate truth values is explicit in the decision table
  • The rules are consistent
    • Every combination of predicate truth values results in only one action or set of actions

Guidelines and Observations

• Decision Table testing is most appropriate for programs where
  • There is a lot of decision making
  • There are important logical relationships among input variables
  • There are calculations involving subsets of input variables
  • There are cause and effect relationships between input and output
  • There is complex computation logic (high cyclomatic complexity)
• Decision tables do not scale up very well
  • May need to
    • Use extended entry decision tables
    • Algebraically simplify tables
• Decisiontablescanbeiterativelyrefined
  • The first attempt may be far from satisfactory
• Lookforredundantrules
  • More rules than combination count of conditions
  • Actions are the same
  • Too many test cases
• Look for inconsistent rules
  • More rules than combinatioion count of conditions
  • Actions are different for the same conditions
• Look for missing rules
  • Incomplete table

Decision Table Examples